1 hour ago, The Terrible Triplett said:

1 - GTI = Grid Tied Inverter

Oeps, my bad ... scanned too fast.

Saw hybrid and GTI in same sentence and thought hold on ...

Coming back to the question:

1 hour ago, Jaco de Jongh said:

So we are actually wrong when we refer to a Hybrid as a Grid tie inverter? 

A Multigrid is a hybrid (as it has batteries), it is connected to the DB board / grid, it can feed back into the grid, can be limited ito what it feeds back and it must conform to anti-islanding rules, same as a GTI without batteries.

So a hybrid is a GTI with batteries, yes?

6 hours ago, Jaco de Jongh said:

So we are actually wrong when we refer to a Hybrid as a Grid tie inverter? 

A hybrid has grid-tie ability  but is a halfway house between GTIs and off-grid inverters. Hybrids have an input and an output and the ability to mix solar/grid power and

the ability to feed into the grid. Hybrid = "item composed of two different elements" - in this case the GTI capability and the off-grid ability.

6 hours ago, Jaco de Jongh said:

Isn't this exactly the same as feeding back into the grid? And if it is, i dont fully understand the following statement...

I think of the grid as the bit that the utility owns the wiring before your meter. We may be talking cross purposes here. I think of the piece after meter as the grid supply but don't think of it as part of the grid (maybe I should change my views). So it you think of the wiring in your house as a hosepipe between the meter and your load then GTIs T into this supply. Due to the grid limiter the GTI is supporting your loads and not necessarily feeding back into the grid.

7 hours ago, Jaco de Jongh said:

Are you referring to prevent it from feeding back in the case of a power failure? 

No I was thinking of a grid limiter acting as a one way valve after the meter that "isolates" the household with a GTI from feeding back into the grid. Now that you have pointed it out my statement is ambiguous and could refer to anti-islanding (prevent feed back during power failure) or grid limiting (prevent feedback under normal operation).

1 hour ago, Chris Hobson said:

We may be talking cross purposes here.

I think its a matter of perception, but i have an better idea now of what was done here. 

Imo, the GTI in question, without any outputs, must apply the same principle as Grid feedback to send the AC back on its "input". Then the Grid limiter sees that only your load gets supplied and no extra is sent to the UTILITY GRID. (Not sure on how they do that yet)

About 2 years ago, myself and I think cvanzyl use to switch our grid feedback on, but our non essential loads connected straight to the grid, consumed the feedback before it reached our meters. In this case nothing reached the Utility Grid.  I guess that is exactly what you have done above. 

2 minutes ago, Jaco de Jongh said:

Imo, the GTI in question, without any outputs, must apply the same principle as Grid feedback to send the AC back on its "input". Then the Grid limiter sees that only your load gets supplied and no extra is sent to the UTILITY GRID. (Not sure on how they do that yet)

100% correct. There are 3 CTs which monitor each phase and the meter has the voltage sine wave of the supply too. So continuously sampling voltage and current the meter is able to detect reverse flow and instruct the inverter to produce less power maintaining a balance.

6 minutes ago, Chris Hobson said:

(Not sure on how they do that yet)

 

6 minutes ago, Chris Hobson said:

There are 3 CTs which monitor each phase and the meter has the voltage sine wave of the supply too.

Thanks Chris, this makes perfect sense now. 

14 hours ago, Jaco de Jongh said:

So we are actually wrong when we refer to a Hybrid as a Grid tie inverter? 

No. Well I don't know how the others do it, but the Multiplus closes the backfeed relay (ie the input is connected to the output), and then it feeds power into this combined connection. So in this configuration it is very much grid-tied. When there is an outage, the backfeed relay opens, but the inverter remains on and it powers the loads on the output.